HTTP::Body versions before 1.23_01 for Perl lose track of chunk boundaries in chunked request…

Why it is Amber

• CVSS 9.1 critical
• Remotely exploitable without logging in

References

• https://github.com/libwww-perl/HTTP-Body/commit/5869dde9fe6d13f189a435b6583fd63fcc18677a.patch
• https://metacpan.org/release/GETTY/HTTP-Body-1.24/changes

Original description

HTTP::Body versions before 1.23_01 for Perl lose track of chunk boundaries in chunked request bodies when a read ends inside a chunk. In chunked mode, used when no content length is given, add() treats a chunk as complete once the buffer is as long as the chunk's declared size, but the buffer still holds the chunk-size line. When a read ends in the last bytes of a chunk, add() takes the chunk short and parses the leftover data as the next chunk-size line. A remote attacker can make a chunked body never complete, hanging a server that reads until the body is done, and may make it complete early, leaving the remaining bytes to be read as the next request.